1. Field of the Invention
The present invention relates to a method of formatting a disk recording medium in which data recording area is divided into plural zones in the radial direction, and defect information is managed for each of the plural zones, a recording medium that is formatted by this method and an apparatus for recording and reproducing digital information using the disk recording medium.
2. Description of the Prior Art
Recently, a process time necessary for formatting (i.e., initializing) a disk recording medium such as an optical disc or a magneto-optic disk becomes longer because of high density and large storage capacity. For example, a magneto-optic disk (MO) having the storage capacity of 1.3 gigabytes that has been in the practical use recently requires approximately 20 minutes of process time. A magneto-optic disk having the storage capacity of 2.6 gigabytes that is under development will requires nearly an hour of process time for formatting process. The term “format” in this specification means so-called physical format.
In the formatting process, certification is performed, i.e., a predetermined bit pattern is recorded over the entire data recording area and reproduced for verifying. If a defect (a defective sector) is detected, an alternative sector is assigned, and a list of the alternation information is recorded in a management information recording area that is called a defect management area (DMA). Normally, four DMA areas are provided to a disk recording medium, i.e., two at the most inner radius and two at the most outer radius of the disk, and memorize the same alternation information.
A recent disk recording medium normally has a data recording area that is divided into plural zones in the radial direction. A rotation speed is changed for each zone in the ZCAV type, while a linear speed for reading is changed for each zone in the ZCLV type. A spare area for the above-mentioned alternative sector is provided to each zone. For example, the data recording area of a magneto-optic disk having the storage capacity of 640 megabytes is divided into eleven zones, while the data recording area of a magneto-optic disk having the storage capacity of 1.3 gigabytes is divided into eighteen zones. In accordance with the kind of a disk recording medium, a term “band” is used instead of “zone”.
Conventionally, in an inspection stage of a disk recording media, for example, the above-mentioned formatting process is performed by a unit of plural sectors sequentially from the inner radius to the outer radius of the disk recording medium or in the opposite direction. For example, in a magneto-optic disk having storage capacity of 128 megabytes, 230 megabytes, 540 megabytes or 640 megabytes, a logical start address (LBA0) is located in the most inner radius. In these magneto-optic disks, the formatting process is performed sequentially from the inner radius to the outer radius. In a magneto-optic disk having storage capacity of 1.3 gigabytes, a logical start address (LBA0) is located in the most outer radius, and the formatting process is performed sequentially from the outer radius to the inner radius.
An example of the conventional formatting process will be explained with reference to FIGS. 1 to 3. FIG. 1 is a block diagram concerning the formatting process of the conventional magneto-optic disk drive. FIG. 2 shows a table of the order of the formatting process. FIG. 3 is a flowchart of the formatting process.
When a host 11 issues the command for a formatting magneto-optic disk 13 to a magneto-optic disk drive 12 (Step #101), a formatting portion 14 of the magneto-optic disk drive 12, as shown in FIG. 2, determines the formatting order of zone of the magneto-optic disk 13 in accordance with the ascending order of the logical address (Step #102). Erasing, writing and verifying processes are performed for each zone. If an error occurs, retry processes are repeated for predetermined times (Step #103). Write data are initializing data that can be set, e.g., a hexadecimal value “CF23” as a default value.
If the error is not canceled by the retry (YES in Step #104), the sector is considered to be a defective sector, and an alternative sector is assigned and defect information (i.e., a primary defect location; PDL) is registered in the DMA (Step #106). Before Step #106, it is checked whether the accumulated number of defects has exceeded the allowable total number of defects (Step #105). The allowable total number of defects is determined as a standardized value in accordance with the kind of a recording medium. For example, total 4,437 defects are allowed to a magneto-optic disk having the storage capacity of 1.3 gigabytes. If the number of defects has exceeded the standardized value, the magneto-optic disk drive 12 halts the formatting process and informs the host 11 of an error that the number of defects has exceeded the standardized value, i.e., of a defect number exceeding error (Step #110). In this case, the magneto-optic disk 13 cannot be used since the formatting process has not been completed.
If the number of defects does not exceed the standardized value, the formatting process continues. When the format of the designated zone has finished (YES in Step #107), the next zone is formatted by repeating the formatting process. When all zones have been formatted (YES in Step #108), the magneto-optic disk drive 12 informs the host 11 of normal completion of the formatting process (Step #109) and finishes the process.
The above-mentioned physical format is performed for erasing all data of a recording medium or for reexamining a recording medium and reregistering defective sectors so that the recording medium can be used securely after long term use has increased errors or elongated access time of the recording medium.
As explained above, since the conventional formatting process is performed sequentially from the inner radius to the outer radius of the disk recording medium or in the opposite direction in accordance with the ascending order of the logical address, the defect number exceeding error can occur in the final zone or just before the final zone. In this case, the process time used for the formatting process before that is wasted since the recording medium cannot be used. As mentioned above, almost 20 minutes can be waste in the case of formatting a magneto-optic disk having the storage capacity of 1.3 gigabytes.
This time loss can be an obstacle to productivity improvement in an inspection stage of a disk recording media. In addition, when a user performs the physical format of a disk recording medium, it would not be endurable if the recording medium cannot be used because of formatting error after waiting for the long formatting process time.
Furthermore, a user has to wait a long time before the physical format is completed in the conventional formatting process even if only a part of the recording area of the recording medium is used, since the conventional formatting process performs the physical format of all areas.